A variable valve mechanism disclosed in JP-A-2006-161730 includes: a control shaft, which is capable of varying the rotary angular position continuously or stepwise; a control member, which is mounted on the outer circumferential surface of the control shaft to rotate together with the control shaft; and a change mechanism, which changes the valve operating angle relative to camshaft rotation in accordance with the rotary angular position of the control member. In this variable valve mechanism, the control shaft is shared by a plurality of cylinders while the control member is provided for each cylinder.
In the above variable valve mechanism, the valve operating angle may vary from one cylinder to another due to a component part manufacturing error or assembling error. Therefore, the above variable valve mechanism includes an adjustment mechanism, which equalizes the valve operating angles of all cylinders as described below. An insertion hole is made in the control member. Further, a protruding part, which is formed to be smaller than the insertion hole in circumferential width, is positioned to protrude into the insertion hole from the control shaft. There are gaps between the protruding part and the left and right circumferential wall surfaces of the insertion hole. Adjustment members (adjustment shims) are placed in the left and right gaps. The mounting angle of the control member relative to the control shaft can be adjusted by replacing the left and right adjustment members with those having a different shape. When the adjustment is made for all cylinders, the valve operating angles of all cylinders can be equalized.
Patent Document 1: JP-A-2006-161730
Patent Document 2: JP-A-2005-9446